Have you seen the long thread from several months ago on induction and griddles? If you haven't, you might find it useful for some additional info on brands.

When I've used burner-spanning griddles on induction ranges and cooktops in the past, I noticed that they could exhibit some of the same behaviors as when doing that on gas ranges -- that is, the heat tended to be over the burners and not as strong in the area betweeen the burners. This didn't matter to me since the space between the burners was only about 2" or so, and I wasn't making tiny pancakes. FWIW, I was using a 10 x 20 Lodge cast iron griddle. But, if you are cooking many strips of bacon or such, some of those strips might take a bit longer to finish cooking than the ones over the burners.

I'm also curious if anybody has tried a larger griddle like the Chef King carbon-steel 14 x 23 griddle. I've only read about them being used on cooktops. Most induction ranges have trim along the edges of the stovetop (and a backsplash vent riser for freestanding induction ranges). I don't know wherther or not one of the larger griddles would bump up against that trim

Many induction cooktops allow you to span two elements. Some are reported to have a bridge element, but I don't know if that means there are inductors all along the bridge, or if that's just the pairable elements. Usually, when there's power sharing, the elements that can be bridged are a pair that share power. Part of the issue with covering two elements is heat build-up and whether it'll lead to cracking. That's a reason to only use the rings that the manufacturer designates.

There's another aspect to the story, however. If you have a big double element, you can use it with a big round griddle. Some people use cast iron pizza pans/stones. I lusted for the old Demeyere teppanyaki style big round for years but totally missed it when they were selling them off at Best Buy, and had to get one slightly used off of eBay. I haven't had a chance to use it yet.

Before I got the big round, I found I liked my thin carbon steel DeBuyer lipped crepe pans best for the kind of things you put on a griddle, eggs and pancakes, etc.

One thing about induction is that even when one's current pans are all good for induction, one tends to use them differently, and learns different ways of doing things. It's gradual, but it happens as one gets comfortable with the new stove. My Le Creuset enamelled cast iron and steel started on electric coil, continued on gas, and now works on induction. My old favorite pot, the 2.5 qt. soup pot, is now one of my least used. It's flared, and is great for gas, using a lot of the waste heat up the sides, concentrating heat in the bottom, and exposing a large surface for reduction, etc. On induction, it takes awhile to heat the sides of the pot since only a small part is in contact with the stove. My new go-to is my old not-so-much two quart combi- saucepan, with a flat bottom and straight sides. Both work fine, but differently.

Regarding a long griddle, if it's cast iron, steel or mutli-ply, it'll work, as in get hot. Just like on gas, there will be hot spots over the inductors, though those lessen the longer the griddle is hot. You might consider preheating it in the oven. It takes awhile for the heat from the part the magnets get excited to spread through the rest.

Consider a big round, or a couple of medium sized rounds, as an alternative. And see if you can find a place that will allow you to try out the possibilities.

Thank you both for you thoughtful and informative responses! It's much appreciated.

I need to consider how well a round pan might work for my cooking style. Also, I appreciate so much the explanation of the heat spread, as I'm unfamiliar with that part of induction cooking. Thanks again!

Twobelles
I use a square griddle and it works fine. I let it warm up to allow the corners to get warmer. Mine is the all clad griddle. It is non-stick and one of the only non stick items that I have.
I do have an electric griddle if I am serving a large crowd.
I also use the LeCr grill pan for panini style sandwiches.
I chickened out in a "bridge" griddle even though the wolf guy said it would be OK.
The key is where do the wires run from each burner so you don't cook over them.

The LG LCE30845 induction cooktop is delivered with a matching griddle to fit over the two left side bridging elements. If you like that griddle, it will address your problem entirely. We use the griddle regularly on our LG induction cooktop, and it works well.

The LG griddle is a rounded corner rectangle with outer dimensions, including handles, of 19-3/4' on the long side by 8-3/4' on the short side. The actual useful cooking surface is 16-1/2' x 7-1/4' inside the lip. The integral handles at the ends of the griddle get very hot, and the griddle must be handled with pot holders while cooking.

The LG griddle is made of stainless steel, and when new it is very highly polished, like a mirror. That polished surface will stay mirror-like for about 30 seconds into the first time you use it, because the Rockwell hardness of the stainless steel is rather low, and it gets tiny microscratches -- burnishing -- immediately. You can use silicone or nylon spatulas or flippers, sure; but if you salt any food on the griddle, the salt grains will burnish the surface; just about anything will burnish the surface. The burnishing does not affect functionality or make the griddle harder to clean, but if you want a mirror-surface griddle, look elsewhere.

The largest single burner on our LCE30845 is eleven inches in diameter, and it heats our vintage Griawold cast iron round griddle evenly.

I hope you find this information helpful.

Here is a link that might be useful: LG's web page for the LCE30845

When I posted the message above about the LG induction cooktop and its included griddle, I expected that I shoud have no trouble finding an image of it online, but a quick search turned up none.

As luck would have it, my spouse cooked two rashers of bacon and a couple of fried eggs at the two ends of the griddle this morning, and that allowed me to snap a picture of the griddle after use in which the departed bacon's footprint shows that on the bridged elements, the heat is distributed uniformly through the entire length of the griddle, including the third element bridged area between the two round burners. You can also see the surface burnishing after six and a half years' use of this griddle.

Thank you all so much! I will definitely investigate both of these possibilities. That Garland unit looks wonderful; it would be fun to cook on, for sure.